Cartridge-fuse



R. C. COLE.

`CARTRIDGE FUSE.

APPLICATION FILED 1^N.24.192o.

'1,396,731 y Patented Nov. 15, 1921.

vwawtoz UNITED STATES PATENT OFFCE..

ROBERT C. COLE, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE JOHNS -PRATTCARTRIDGE-FUSE.

To @ZZ whom t may concern Be it known that l, ROBERT C. COLE, citizen ofthe United States, residing at Hartford,y in the county of Hartford andState of Connecticut, have invented a new and useful Improvement inCartridge-Fuses, of which the following is a specification.

This invention relates to the construction of non-renewable cartridgefuses of the knife blade type.

The object of the invention is to provide a casing for a fuse of thisclass comprising parts which are simple to make and easy to puttogether, and which when once assembled cannot be taken apart or enteredwithout special tools and `the destruction of or irreparable damage toessential elements.

This object is attained by locking the knife blades with key plates soshaped that when ittedftogether they close the endsof the tube, andwhich have lugs that slide into and lit undercut mortises in the ends ofthe tubes, and holding the key plates in place by the caps which engagewith the edges of the lugs so that the caps cannot be removed after oncebeing set without destruction or damage.

'Figure l of the accompanying drawings shows a side view of a knifeblade fuse constructed according to this invention with one half cut incentral section. Fig. 2 shows an edge view with one of the caps brokenaway. Fig. 3 shows a section of the tubular casing. Fig. 4 shows a.transverse section on the pla-ne indicated by the dotted line 4 4 onFig. l. Fig. 5 shows a face view of one of the lock plates. Fig. 6 showsan edge view of the lock plate. Fig. 7 shows a face view of one of thecaps. Fig. 8 shows a section of the cap.

The body of the casing consists of a tube l of fiber or other suitableinsulating material. In each end of the tube diametrically opposite eachother two dove-tail or undercut mortises 2 are punched or otherwiseformed. The terminal blades 3 are formed of copper in the usual mannerand are connected inside of the casing by any type of fusible link 4. Oneach blade just inside of the end of the tube a plate 5 is secured insuch manner as to provide recesses 6 at the end of the tube between theinner edges of the wider part of the blade and the plate. These recessescould be, of course, made any desirable depth by simply cutting awaySpecification lof Letters Patent.

Patented Nov. 15, i321.

Application filed January 24, 1920. serial No. 353,752.

more or less of the edges of the wider sections of the blades. Each endof the tube is closed by a pair of key plates 7, each plate beingsubstantially semi-circular and having a slot 8 that tits the blade anda dove-tail lug 9 designed to enter adove-tail mortise in the kend ofthe tube. T hese key plates are thrust together-on the blades fromopposite sides over the ends of the tubes, and when each pair iscompletely together and the ends of the tube are closed thereby thedovetail lugs lie in the dove-tail mortises in the tube so that the keyVplates cannot move lengthwise of the tube. After these parts are inposition the caps 10 with slots 11 that just iit the blades are slippedover the blades and onto the endsof the tube over the key plates. Whenin place the caps hold the key plates from moving transversely andunlocking the blades. After the caps have been put in place their inneredges may be spun down over the ends of the key plate lugs or the capsmay be provided with internal shoulders l2 at their inner edges and thekey plates so .formed that when assembled the lugs may project beyondthe surface of the tube, then when the caps are slipped on, the lugswill yield until after the caps have reached their vclosing position, atwhich time the lugs will be free to spring outward slightly and engagethe shoulders around the inner edges of the caps and thus prevent .thecaps from withdrawal.

lVith this construction the caps hold the key plates from radialdisplacement and cover the joints between the key plates, and the keyplates with their lugs entering the dove-tail mortises in the tubeprevent the blades from rotating and from moving longitudinally inwardor outward of the tube. .lt is preferred to make the key plates of veryhard metal so that it will be difficult for anyone to drill a holethrough them for the purpose of inserting a conducting wire. Thisconstruction is very easy to assemble and yet it is very diflicult totake apart, or to restore it after the fuse link is once blown withoutvisible indication of the fact that the casing has been tampered with.The casing may or may not be filled with'the usual condensing andabsorbing materials.

The invention claimed is l. A cartridge fuse comprising a tubularinsulating casing having undercut mortises in ends, Contact terminalsextending lio through the ends of the casing, a fusible link connectingthe terminals Within the' casing, key plates engaging the terminals andhaving lugs itting the mortises in the'ends of the easing, and capsthrust upon the ends of the casing over the key plates and held againstremoval thereby.

2. A cartridge fuse comprising at-ubular insulating casing havingundercut mortises in its ends, contact terminals extending throughtheends of the casing, a Vfusible link connecting the terminals Within thecasing, key plates engaging the terminals and having lugs fitting themortises in the ends of the casing, and caps thrust upon the ends of thecasing overY thkey plates and holding the plates against transversedisplacement, saidcaps having their inner edges extending diametricallyinward over the inner ends ot. the key plate lugs and held on the casingthereby.

V3. A cartridgejfuse comprising a tubular insulating casinghavingundercut mortises in its ends, contact terminals extending through theends of the casing, a fusible link connecting the terminals within thecasing,

key plates engaging the terminals and having lugs fitting the mortisesin the ends of the casing, and caps thrust upon the endsof the casingover the key plates and holding them against removaland being heldagainst removal thereby. Y

4. A cartridge fuse comprising a tubular insulating casing havingdove-tail mortises in .itsV ends, Contact terminal blades extend- Aingthrough the ends of the casing, key

plates engaging the terminal blades and having dove-tail lugs 'fittingthe mortises in the ends of the casing, and caps having slots fittingthe terminal blades slipped longitudinally upon the ends of the casingand holding the key plate lugs in the mortises in the tube.

5. A cartridge fuse comprising'a tubular insulating casing havingundercut mortises in itsl ends, contact bladesvvith recesses in theiredges extending through the ends of the casing, key plates fitting therecessed seetions of the blades and having lugs ittingk the mortises inthe ends of the casing, and

capshaving slots iitting the terminal bladesl slipped longitudinallyupon the ends of the casing over the key plates and holding the platesVagainst transverse displacement and held from longitudinal displacementthereby.

6. A cartridge fuse' comprising a tubular insulating casing havingundercut irmortises in its ends, contact blades extending through theends of the casing, anchor plates fastened on the blades Within thecasing, key plates engaging the blades outside of said anchor plates andclosing the ends of the casing, said plates having lugs fitting themortises in the ends of the casing, and caps thrust upon the ends of thecasing and formed inward over the'key plate lugs.

7. cartridge fuse comprising a tubular insulatingV casing havingundercut mortises the ends of the casing, anchor plates fastened on theblades Within the casing, semicircular lkey plates ittedtogether andclosing the ends of the casing about the blades outside of said anchorplates, the joints between said key plates being covered within by saidanchor plates, lugs extending at substantially right angles from thekeyv plates and Vittingthe mortises in the ends of the casing, and capshaving slots tting the blades thrust'v longitudinally upon the ends ofthe casing over the key plates andholding the key plates againstktransverse displacement.

. in its ends, contact blades extending through n 8. A cartridge fusecomprising a tubular i thereby from `movement longitudinally of thecasing and in engagement with the blade and 'therebyholding' the vbladefrom movement longitudinally ofthe casing, and a cap located on theendofthe casing over the key plates and holdingthem in' place and heldagainst removal thereby.

nosniar o. conn.

